Small-Block RC Gas Engine Guide — A New Generation of compact Power!

Small-Block RC Gas Engine Guide — A New Generation of compact Power!

Lately, there has been a noticeable shift toward smaller displacement single-cylinder, gasoline engines and there are now many of these little gas-burning powerhouses on the market. Years ago, when you talked about gas engines, the smaller end was owned by the 25cc engines and the average size was roughly between 40cc and 60cc with a few exceptions. Gasoline engines have also grown to monstrous sizes in the 150 and 200cc ranges with other multi-cylinders radials sporting 400cc. I guess it’s only natural that smaller engines have come along to try and balance out the size spectrum.

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Updated: July 20, 2015 — 12:25 PM


  1. Now if ARF manufactures would produce planes that are designed specifically for these small engines and their ignition systems. There are only a few models out there.

  2. I have a RCGF 15cc that runs flawlessly. I’m looking for a new aircraft for it. It seems that since the power is equivalent of at least a .60 nitro engine, there should be a lot of choices of aircraft but not so. It seems there a lot of .40 powered craft out there. There don’t seem to be many designed for a .60. The engine is pretty big and heavy for a .40 powered airplane.

  3. I have started switching from nitro to gas engines and my only question is: with ethanol in the gas will it hurt to use Aviation gas even though it is about 100-103% octane. I believe there is no ethenol in it.

    1. I have heard of modelers using Av-gas with little or no problems. Also, Coleman stove fuel “White Gas” can also be used, and has no ethanol. It is getting harder to find gas stations without some percentage of ethanol added.

      1. Keep in mind 100LL avgas has a very large amount of lead, (4 times the amount per gallon that the old leaded mogas) 100LL has 2mg of tetraethyl lead vs. .5mg per gallon of the old leaded car gas. Coleman fuel is about 65 octane. Mix the 100LL and Coleman 50/50 and you should be fine.


    2. I have an app on my iPhone called Pure Gas that shows me all the stations in my area that have ethanol-free gasoline. I NEVER put ethanol in ANY of my small engines since I screwed up an outboard boat engine with FOUR carbs on it!!

  4. I came back into the hobby after almost a 20 year break and picked up an 800 class gas helicopter. I love it. Super easy to start, runs an easy 45 minutes to spare. The best part, all I need is the helicopter, my transmitter and a jug of gas.

  5. I’ve been told that these motors are much noisier that equivalent glo motors. Is this the general rule?

    1. Where are the O.S. GT15 and GT22 gas engines? Big omission IMO.

      1. Thanks for your comment Rob. This article was published a while ago, so did not have the new O.S. engines included. When I get a chance I will add the engines to the roundup!
        thanks for writing!

    2. The noise an engine makes really depends on the type and quality of the muffler used. Some of the included stock mufflers might not be as efficient as aftermarket ones but in general, they are in the same range as Glow engines. Also with RPM being a factor, Gas engines do their work best at lower RPM ranges so here it will be making less high frequency noise. Hope this helps

    3. I have had noise level tests run on my gas engines at events, and they were somewhat quieter than most nitro engines. They normally run larger props at lower rpms, and have a deeper sound which gives a perception also of being quieter and more pleasant. Of course in the long run, it depends on the muffler and how the engine is propped, and the type of airframe which can contribute to the overall sound. You can’t compare their noise to “chainsaws” or “weedeaters” which operate at considerably higher rpms.

  6. The gasoline engines in this size range are not any louder than it’s equivelant nitro burning engine. The reliability, ease of use, cost to run, and the fact they are MUCH cleaner (not near the oil residue) make these the only way to go!! I’ve been using gas engines for years now (30cc to 120cc) and they are by far the best way to power your model… unless you’re an electric fan.

  7. will be that some of these engines work for
    600 or 700 size helicopters

  8. Question: Currently we do not allow gas engines at our fielsd because of noise issues. How do these new smaller engines compare to comparable nitro engines from a noise standpoint?

  9. For you gas burners out there, I heard that Shell 92 octane has no ethanol in it. I recall reading this in RCU while surfing the site.

    1. In all cases, read the label on the pump, but consider this. The hose on most of today’s pumps from the switching valve to the nozzle is full of what the last customer bought. Now this may not make a lot of difference if you are filling up your car, but if you are just getting a gallon for your models, think of the quantity that long big hose has in it. Hmmmmm.

      1. Before filling your gas can, put the first couple of gallons into your vehicle, this should clear the gas pump hose of any residual gas with ethanol in it.

  10. I suspect the amount of noise any engine produces is a factor of its muffler. Since gas engines run at lower rpms that glow, I think in general they do not make more noise. IMO.

  11. I know over here in Canada we are allowed to have up to 10% by volume of Ethanol in the gas. I am not a 100% sure on the high grades such as Ultra94 or Super. I don’t “think” they do. Anyone know of a test that can be preformed? Without needing a degree in chemistry?

    1. Simple to check.use measuring cup,put water in to first measuring line. Fill cup with fuel.if the water line rises fuel has alcohol in it. Alcohol is clear and is attracted to water. Sometimes additive in the fuel will make a milky line separating fuel and alcohol ,water mix. Hope this helps.

  12. I wish when people show oil to fuel ratio’s they would indicate if the measurement is in U.S. Oz./Gal. or imperial/U.K. Oz./Gal. I hate having to convert all the time or have to find out where the info came from. This is an international web site. Maybe the best solution would be for the U.S. to catch up to the rest of the world and adapt to metric. ml:L or show both U.S. & metric or U.K. & metric.


  13. If you can find a gas station that sells recreational fuel you should be good to go. Its not supposed to have ethanol in it which is why the boaters use it

  14. The new OS GT-15, bought new in box, was nearly impossible to start with factory-set fuel mixture screw settings. Finally, in desperation, I opened the fuel mixture screw about 30 to 45 degrees to get fuel to the engine, and that adjustment worked, contrary to the Owner’s Manual which said to leave the fuel mixture screw ALONE. I am unable to get more than 6800 RPM from the engine with a 15 X 8 prop, which is insufficient to fly my new 13-pound 60-size kit-built Sea Fury. The Owner’s Manual states 11,000 is the maximum practical RPM, but I cannot get anywhere near that speed even with 100 octane aviation gas (the only way to avoid alcohol in the gasoline).
    What steps should I take to get more speed from this engine?

    1. Avaition 100 octane LL has a much lower vapor point than automobile gasoline.. Airplains operate at much higher altitudes than model airplanes and cars so auto gas would be more likely to vapor lock in an airplane enviromant than in a car (engine). This is even more true now that auto gas is Low Lead I think. Also most cars are fuel injected now.

  15. Culd you recommend me the most reliable and powerful aircraft engine?

  16. I miss an indication of the fuel consumption….

  17. If you are near a marina or any place that sells boating fuel you will probably find non ethanol fuel.

  18. I wonder when, or if the boating community will have these engines available. Has anyone seen any of these that run in the opposite direction?
    I would like to try a 10cc Hobbico in a 60 size boat.

    1. I’m actually here wondering the same thing. I would love to see a graph of all these engines showing power, torque, and gal/hr fuel consumption vs. RPM.. and comparing each other this way. This would allow picking the optimum engine for the application, for those with some real engineering background.

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